Comparison between the effect of isoflurane and sevoflurane on left ventricular diastolic function in patients with pre-existing diastolic dysfunction undergoing CABG

ABSTRACT

Inhalational anesthetics have been shown to possess a dose-dependent negative lusitropic action in experimental studies. This effect was explained by the interference of inhalational anesthetics with calcium homeostasis at several subcellular levels. However, effect of inhalational anesthetics on diastolic function in humans is still controversial. The aim of this study was to compare the effects of isoflurane and sevoflurane, two of the most commonly used inhalational anesthetics in cardiac surgery, on left ventricular diastolic indices as measured by transesophageal echocardiography [TEE] in patients with pre-existing diastolic dysfunction. After approval of the local ethics committee and obtaining written informed consent, 40 adult patients with pre-existing diastolic dysfunction were randomly allocated to one of two groups. Group I [n=20] received isoflurane, while group II [n=20] received sevoflurane as the maintenance anesthetic. Induction agents and other maintenance agents were standardized in both groups. Changes in hemodynamic parameters and echocardiographic indices before and after drug administration were compared. Filling pressures during the study were kept constant within normal range by infusion of intravenous fluids. Hemodynamic changes measured by invasive arterial pressure and pulmonary catheter were comparable between isoflurane and sevoflurane groups. Both led to a significant reduction in afterload that was accompanied by a significant increase in cardiac output and stroke volume. Transesophageal echocardiographic relaxation indices were also comparable between both groups. Transmitral and tissue Doppler E-waves increased significantly in both groups, leading to larger E/A and Em/Am ratios; whereas the deceleration time and the isovolumetric relaxation time decreased significantly. Also there was a significant increase in color M-mode transmitral propagation velocity [Vp] in both groups. Both isoflurane and sevoflurane caused an improvement in TEE diastolic indices in patients with preexisting diastolic dysfunction. However, there was no difference between the two agents. This improvement could be attributed to a reduction in left-ventricular loading conditions